Uniform Jump (AMI) - Boundary Condition Description
Uniform Jump (AMI) is a boundary condition that imposes a fixed difference (jump) in field values between a pair of cyclic AMI patches. Unlike the standard Uniform Jump (AMI) where the jump can vary across the surface, here the jump is spatially uniform but can vary in time.
This condition is typically applied to the owner patch of the cyclic interface and is useful for modeling global transient effects, such as a time-varying pump pressure rise or a fluctuating heat source at an interface.
- \(\phi_{n}\) - field value on the neighbor patch
- \(\phi_{o}\) - field value on the owner patch
- \(J(t)\) - specified spatially uniform jump value (time-dependent)
Uniform Jump (AMI) - Boundary Condition Understanding Uniform Jump (AMI)
The Uniform Jump (AMI) is applied to patches that are already coupled via a cyclic or Arbitrary Mesh Interface (AMI). It maintains an offset between the mesh regions that changes over time. The key characteristics are:
- Uniformity: The offset \(J\) is identical for every face on the patch at a given time instant.
- Time-dependence: The offset \(J\) can change during the simulation based on a table or csv file.
This allows for modeling dynamic systems where the "strength" of the discontinuity evolves, for example, ramping up a fan pressure during startup.
Uniform Jump (AMI) - Boundary Condition Application & Physical Interpretation
The Uniform Jump (AMI) is useful in transient simulations involving interface discontinuities.
Transient Turbomachinery
Context: Simulating the startup or shutdown phase of a fan or pump modeled via AMI interface.
Physical meaning: The pressure rise (jump) across the fan increases or decreases over time as the rotational speed changes.
Dynamic Heat Sources
Context: Modeling a heating element at an interface where power output fluctuates.
Physical meaning: The temperature jump across the thin layer varies with time according to the power input.
| Variable | Owner Patch | Neighbor Patch |
|---|---|---|
Pressure | Uniform Jump (AMI) | cyclicAMI |
Velocity | cyclicAMI | cyclicAMI |
Uniform Jump (AMI) - Boundary Condition Uniform Jump (AMI) in SimFlow
The Uniform Jump (AMI) is available when an Arbitrary Mesh Interface (AMI) has been created between two patches in the Mesh panel. To apply it, select the AMI patch in the Boundary Conditions panel and choose Uniform Jump (AMI).
Jump Table - Defines the time-dependent offset value \(J(t)\). Can be defined using a table or function.
Uniform Jump (AMI) - Boundary Condition Uniform Jump (AMI) - Alternatives
In this section, we propose boundary conditions that are alternative to Uniform Jump (AMI). While they may fulfill similar purposes, they might be better suited for a specific application and provide a better approximation of physical world conditions.
| Boundary Condition | Description |
|---|---|
Similar to Uniform Jump (AMI), but the jump can be spatially varying (a field) and is typically constant in time. | |
Standard cyclic coupling with no jump (\(J=0\)). Ensures continuity of the field across the interface. |